Method for making thermoplastic particles



Dec., 22, 1959 R. K. PETRY 2,917,780

METHOD FOR MAKING THERMOPLASTIC FARTICLES B im A TTORNEY Dec. 22, 1959R. K. PETRY 2,917,780

METHOD FOR MAKING THERMOPLASTIC PARTICLES Filed Aug. 23. 1952 2Sheets-Sheet 2 A TTOR/VEY United States Patent O METHOD FOR MAKINGTHERMOPLASTIC PARTICLES Robert K. Petry, Wilmington, Del., assignor toConn goleum-Naim Inc., a corporation of New York Application August 23,1952, Serial No. 305,994 12 claims. (c1. 1s`4s.s)

This invention relates to method and apparatus for making thermoplasticcomposition products. It relates especially to method and apparatus forproducing such products in sheet form, and to method and apparatus forproducing products and sheets which are of variegated color. Thisapplication is a continuation-in-part of my application Serial No.43,274 filed August 9, 1948 for Process and Apparatus for ManufacturingThermoplastic Products and of my application Serial No. 93,126 led May13, 1949 for Manufacture of Thermoplastic Resinous Sheet Material, bothnow abandoned.

More specific aspects of this invention relate to method and apparatuswhereby such products may be successfully produced utilizing coloredvinyl plastic composition comprising thermoplastic vinyl resin andfiller.

Features and objects of this invention relate to steps and combinationsof steps and to controls exercised therein whereby thermoplasticcompositions such as a vinyl plastic composition may be successfullyproduced and formed into a product such as a sheet and whereby a sheetproduct may be produced suitable for use in flexible smooth surfacecoverings having either a plain color or a variegated color such as ajaspe or marbleized effect. Other features and objects of this inventionrelate to steps and combinations of steps and to controls exercisedtherein whereby improvements in quality and uniformity are afforded, andwhereby improved appearance is afforded both as regards surface nish andas regards the definition and distinctness of color contrasts in thecase of products of variegated color.

Certain of the objects and features of this invention relate to theemployment in combination of steps and apparatus whereby a vinyl plasticcomposition is produced, is converted into `particulate or granularform, and is formed into a sheet which may be provided with a glossfinish and which, if variegated, may be jaspe or marbleized, and tocertain controls maintained therein which are critical to'obtaining animproved product. While the steps and apparatus are preferably employedin combination certain of the features of this invention relate tosubcombinations of steps and apparatus elements.

In the manufacture of a product such as a smooth surface covering it haslong been recognized that the employment of a thermoplastic compositionwhich is sufliciently hard and tough at ordinary temperatures to beresistant to wear and indentation offers certain advantages due chieflyto the fact that such a composition, if it can be successfully formedinto a satisfactory sheet, is ready for use immediately after coolingfrom an elevated temperature at which the thermoplastic composition canbe worked. Such properties of a thermoplastic composition are to becontrasted with those of conventional linoleum composition which dependson the use in the binder therefor of a drying oil such as linseed oilthat hardens by oxidation. linoleum' typev oor covering the linoleumcomposition is initially prepared using a drying oil which is only in apartially oxidized condition whereby the linoleum com- During themanufacture of a' 2,917,780 Patented Dec. 22, 1959 ICC position atnormal temperatures is of a putty-like con sistency permitting it to bemixed, sheeted and made adherent to a suitable base sheet. However, sucha linoleum type door covering after it initial production is not readyfor use due to the soft putty-like consistency of the layer of linoleumcomposition. In order to harden the layer of linoleum composition it isnecessary to season it and such seasoning requires prolonged exposure toair at an elevated temperature in an operation which is costly both fromthe point of view of the time and labor involved and from the point ofview of the size and cost of the equipment which is required. However,notwith-I standing such disadvantages inherent in the use of linoleumcomposition or the like, the bulk of the flexible smooth surfacecoverings that have been manufactured and sold heretofore have been ofthe linoleum type comprising a molded layer of linoleum composition orhave been of the type wherein a suitable paint or the like is applied toa suitable base sheet as by a printing operation. This has been dueprincipally to the diiculties that have been encountered insuccessfullyformulating and processing a thermoplastic composition whereby acommercially satisfactory product may be obtained. Moreover, whilelinoleum composition lends itself to processing whereby attractive floorcoverings of variegated color may be obtained such as jaspe ormarbleized coverings, especially severe difficulties have beenencountered in connection with attempting to produce such products usinga thermoplastic composition. According to this invention suchdifficulties have been successfully overcome and highly satisfactoryflexible smooth surface coverings have been produced both of plain colorand of variegated color using a thermoplastic composition material. Itis an advantage of this invention that the aforesaid objectives havebeen attained in a manner which is economical and practical and by whichaccurately reproducible results are obtainable at a high productionrate.

One of the features of this invention relates to pro duction of heatplasticized particles of thermoplastic composition by novel method stepsand apparatus whereby under requisitely controlled temperatureconditions a thermoplastic composition is mixed, is sheeted and is madeadherent as a sheet to a rotating roll, the heat' plasticized sheetbeing converted into particles by gouging the particles therefrom whileit is carried in adherent relation on the surface of the rotating roll.l Other fea-v tures of this invention relate to the production of acalendered sheet by the sequential operations of sheeting aA heatplasticized mass of thermoplastic composition, converting the resultantsheet to the form of heat plasticized particles, and calendering theheat plasticized particles.`

Other features of this invention relate to the production of heatplasticized particles of thermoplastic composition having ditferentcolors and the commingling of same to form a mixture of variegated colorimparted by ythe particles and the subsequent calendering of the tion ofa main chain of apparatus employed th process;

Fig. 2 is a vertical section of a heated conveyeremf.

ployed in the apparatus;

Figs. 3, 4 and 5- are viewsshowing details of 4a called gouging `orscratcher roll employed `in the ap? paratus.

Preferred materials employed in Nte process.

ln the preparation of colored plastic products by means of the presentinvention, it is preferable to ein ploy a composition which isthermoplastic and contains no material that requires drying, curing orvulcanization to condition it. Coloring materials preferably in solid,finely divided form are mixed with sutcient binder consisting preferablyof a plasticized, thermoplastic, elastomeric polymer to render va sheetprepared therefrom, solid and compact, and yet flexible lor pliable,resilient, and elastic. The materials are preferably such as willrequire no addition of volatile solvent or moistening agent tofacilitate distribution of the coloring material in the Plastic..

Thettherrnoplastic, elastomeric polymers employed in thepresent,invention are-preferably vinyl polymers in theLhigh molecularweightrange.- Preferred among the latter are thepolymers of vinyl chloride,vinyl acetate, vinyl'butyral, andtcopolymerof vinyl chlorideand `vinylacetate. Acopolymer which has proven satisfactory is oneprepared from 93to 95 percent vinyl chloride and the balance vinyl acetate, with anaverage molecular weight of approximately 24,000 as determined by theStaudinger method, and having a specific gravity of about 1.34 to 1.37,`and softening at approximately 150 F. These above-mentioned polymermaterials, when formed for present purposes, require no chemical orother treatment except preferably the addition of a plasticizer.

Plasticizers are employed which are compatible with these polymers, andwhich contain no constituents that are, as in the case of the polymers,reactive with atmospheric oxygen in the range of atmospherictemperatures. Examples of such plasticizers are tricresyl phosphate,dioctyl phthalate, dicapryl phthalate, dibutyl sebacate, dibutoxyl ethylphthalate, dibutoxyglycol phthalate, polyethyleneglycol di-2-ethylhexoate, triethyleneglycol di-2- ethyl hexoate and the like.

Pigments or fillers employable are, for example, asbestine, barytes,calcium carbonate, calcium sulfate, clay, dolomite, mica, silica, slateour, serpentine, talc. Synthetically prepared pigments, and naturalpigments and others, including chrome green, chrome yellow, carbonblack, titanium dioxide, are used for providing solid colored orvariegated plastic products referred to herein. Dyes miscible orimmiscible with the resins may, in cer tain instances, also be used.

Fibers, such as asbestos, cork, wood our, cellulose bers in general, andothers, including lanimal ber, such as leather, may be added.

The particle size of pigments or fillers should be such that they willpreferably pass through a 325 mesh screen. Fibers, if employed, as forinstance, wood our, should pass through a 50 mesh screen, though finergrades can be used. Asbestos fibers, namely, Vshorts, pass completelythrough a 10 mesh screen.

Traces of lubricants such as stearic acid, and metallic stearates, andof stabilizers such as basic lead carbonate, basic lead silicate, andbasic lead stearate are generally added to the mix.

A mix for preparing a desirably colored plastic material containssubstantially 50% to substantially 75% by Weight of ller material,including color pigment alone or both pigment and` ber. These limits arevaried not more than one to five percent. A ratio of pigment fillertocbrous filler that is particularly desirable for floor and wallcovering, is two parts by weight of pigment to one palgt of weight offiber. Preferably notV more than 50% ofgviiber is, used in the mixedfiller, thoroughly and uni formly distributed.

forpreparing colored-sheets contain in parts by weight from about 16 toabout Bti-parts of the polytions for wear surfaces -are about 23parts-of polymer, about l2 parts of plasticizer, and about 65 parts ofller. A compounded sheet containing the various pigments and fillers inthe proportions stated has a preferred specific gravity of 1.85 to 1.90.Depending on the types of fillers and to some extent the proportionthereof, the specific gravity may be as low as 1.5.

A number of complete formulae of mixes are set forth in Patent No.2,558,378 which resulted frommy application Serial No. 722,291, tiledJanuary 15, 1947. Though specific proportions of materials are statedabove, such proportions are variable in the present process dependingupon the effects desired andthe use of the final product,

Compositions of the character aforesaid which comprise la thermoplastic-vinyl resin and a -ller are referred to herein and in the claims forthe sake of brevity as vinyl plastic composition, and sheets, particlesand the like made therefrom aresimilarly referred to as vinyl plasticsheets, vinyl plastic particles, etc.

The thermoplastic composition such as a vinyl plastic composition ismixed in the mixer 1 at a temperature at which it is of plastic andworkable consistency. The mixed composition is passed from the mixer 1to the sheeter by which it is formed into a sheet While of moldable heatplasticized consistency. The resulting sheet, as will be described morein detail below, is comminuted or reduced to particles or granules byreducing means exemplified by the so-called scratcher or gouging rolladapted to gouge moldable heat plasticizcd particles from the sheet.

The particles or granules -by means of a heated conveyer are conveyed tothe calender by which the heated granules are formed into a continuoussheet.

If a sheet of variegated color is desired plastic cornposition particlesyor granules of a different or Contrasting color, one or more, may beseparately and similarly prepared by means of the mixer, the sheeter andthe scratcher roll. These particles or granules of a different orcontrasting color are commingled with the other particles or granulespreferably by feeding them at a regulated rate by heated conveyer means.In such case the re-` sultant commingled particles consistuting amixture of variegated color imparted by the particles of different colorare passed to the calender by the heated conveyer and the sheet formedby the calender will be of variegated color having a so-called jaspeappearance.

Detailed description and exemplication of invention Certain ofthe-features and advantages of this invention will now be `described andexemplified in greater detail in connection with Figs. l to 5 inclusiveand in connection with the employment of a thermoplastic compositionsuch as a vinyl plastic composition ofthe character hereinaboveexemplified. During processing the composition is maintainedundercontrolled temperatures, which for certain steps is relativelyhigh, the composition remaining moldable at the temperature prevailingduring the steps, while preferably avoiding v.employment of temperaturesso high that the composition employed when molded will not retain itsshape. For obtaining uniform results accurately maintained temperaturecontrols are important, and for obtaining desired effects con trol oftemperature land maintenance of certain ternperature differentials arealso important both from the point of view of .operativcness and theappearance of the product especially in the case of the production ofproducts of variegated color. A vinyl plastic cornposition such ashereinabove exemplified can be conveniently mixed and sheetedwhilem'aintaining the tern-l perature thereof uniformly aboved300 F.andvwhileV certainl of the features of thisuinvention-f-may bepracticedWhile maintaining ,web elevated temperaturesz'the tme- Praturss@scarring in varillsters may .range above. .or below 4500"andjhrnaintenance-of certain temperatures and temperature diereutials ishighly important in the production of certain products according to thisinvention as will more fully appear hereinbelow.

The ingredients of the thermoplastic composition are charged into amixer 20, such as a Banbury mixer which is of suitable heavyconstruction and is provided with means for controlling the temperatureof the materials being mixed therein. In the case of preferred vinylplastic composition of the character yaforesaid the temperature of thecharge is in t'ne approximate range of about 325 F. to about 375 F.although a somewhat lower mixing temperature down to about 300 F. may beemployed in the case of such vinyl plastic compositions which employ arelatively soft vinyl resin or a relatively high ratio of plasticizer tovinyl resin. The materials charged into the mixer may be in theiroriginal raw condition, or may include reworked scrap, or all or aportion thereof may be preblended.v A typical mixing temperature for avinyl plastic composition having good all around properties for use as afloor covering is approximately 350 F. The mixing temperature is thattemperature at which the ingredients become comrningled under theinfluence of the mechanical mixing action to form a substantially heatplasticized workable mass which is substantially homogeneous in thesense that the ingredients are substantially homogeneouslyinterdistributed. The mixing temperature is determined both by the steampressures employed in heating the mixer, and by the large amount of heatwhich results from the `internal friction developed in the materialitself during the mixing operation. Well known means (not shown) areprovided for accurately controlling the mixing temperature, and to makeknown to the operator the actual temperature of the material duringmixing and at the time discharge. The temperature of the dischargedstock is preferably maintained substantially constant. The mixingtemperature desired is attained immediately prior to discharge of themass and when the conditions have been attained at which the resin hasall become fused and homogeneously blended with the other ingredients.This usually requires a mixing period of about 4 to l0 minutes dependingon such factors as the rate at which the mixer is operated, the amountof heat supplied thereto and the size of the batch. The mixingtemperature attained should be suiciently high to obtain such fusion andhomogeneous blending but excessive temperature development may result indegradation of the vinyl resin. ln order to avoid over-heating of thecharge, it should be discharged from the mixer when the desired mixingtemperature is attained.

The next step in the operation is to convert the hot plastic massproduced in the mixer into discrete heat plasticized particles orgranules of moldable consistency, and certain of the features of thisinvention relate to the method and apparatus whereby this result hasbeen successfully accomplished. This conversion of the hot plastic massto heat plasticized particles or granules involves the carrying of a hotsheet formed from the hot plastic mass in firmly adherent relation tothe surface of a rotating roll and the gouging of the particles' orgranules from the hot sheet while so carried by the rotating roll. Theseoperations will now be illustratively described in greater detail.

The hot plastic mass after having been mixed in the Banbury mixer 1 isdischarged therefrom onto a two roll mill or sheeter which comprises therolls 21 and 22, and the operation is carried out so that a supply ofhot plastic mass is maintained for continuously feeding the sheeter. Therolls of the sheeter preferably are in a horizontal position as shown soas to facilitate the feeding of the hot plastic mass therebetween, andcan be adjustably spaced to provide any desired thickness' of sheet.These rolls are driven by a variable speed motor (not shown) and aregeared so that the roll 22 revolves preferably at a greater peripheralspeed than that of the roll 21. Moreover the roll 22 is preferablymaintained at a substantially higher temperature than that of the roll2l, the rolls 21 and 22 being heated as with steam so that theirrespective temperatures may be controlled and so that plastic sheettemperature can be likewise controlled and regulated. When the mixingteun perature is in the above mentioned range the temperature of themixing rolls, and especially that of the mixing roll 22 on which thesheet is carried after its formation, should be in the same range. Forexample, temperatures for the mixing rolls in the approximate range of325 F. to 350 F. are suitable, although a somewhat lower temperature forthe roll 21 of approximately 300 ll?. may be employed. The heat of themixed composition when discharged from the mixer as supplemented by theheat supplied to the rolls and the heat generated by internal frictionduring the sheeting operation serves to maintain the temperature of thecomposition so that it pref erably does not fall below the mixingtemperature and may be somewhat higher than the mixing temperature, asthe sheeted composition is carried on the surface of the roll 22.Maintenance of such temperature conditions is highly important in orderthat the sheeted composition will firmly adhere to the roll 22 and willpossess proper consistency for conversion into particles or granules bygouging them from the sheet While it is carried on the surface of theroll 22; and the fact that heat plasticized particles or granules can be.successfully produced in the manner described if these requisiteconditions are maintained is a significant feature of this invention.When the proper controls were not maintained the operation Wasinoperable due to such occurrences as the sheet becoming stripped whollyor in chunks from the roll 22 when attempt was made to gouge theparticles `or granules therefrom and there was resultant fouling andcomplete failure to obtain particles or granules in a usable condition.By way of a further more specific example when the mixing temperature is`approximately 350 F. a temperature of about 350 F. or somewhat abovefor the roll 22 and the stock temperature of the sheet formed andcarried thereby provides good operating conditions. However, thetemperature control can be varied within the aforesaid temperature rangeof 300 F. to 375 F. depending principally on the particular compositionformulation that is processed. More generally it is preferable to employas high a temperature for the sheeting operation and for the gouging ofparticles from the sheet as i is consistent with minimizing degradationof the vinyl i inherent characteristics of the compositions wherebyunder` the temperature control conditions maintained whereby the formedsheet remains firmly adherent to one of the sheeting rolls, the coactionbetween the sheet, the roll on which it is carried and the action of thegouging members is such that the particles or granules areV effectivelyproduced.

In producing the heat plasticized particles or granules by gouging themfrom the sheet which is formed between the rolls 21 and 22 while thesheet, under the temperature conditions above mentioned, is carried bythe roll 22 in firmly adherent relation thereto, the gouging isperformed using the gouging or scratcher roll 23 which is preferablyhoused in the enclosure 24 that is provided with a transparent orsliding door 25 through which the operations may be observed. As shownin Figs. 3, 4 and 5 the scratcher roll 23 consists of a roll havingnumerous spikes, teeth or gouging pins 26 project# ing from anddistributed in fixed position as on 1 inch. centers over the surfacethereof. The'spikes or pins 26 are removable and may be variously spacedand inserted in staves 27 which fit into axially extending recesses 28in the surface of the roll 23. The roll 23 is `adjustably movable towardor away from the surface of the roll 22 and is set so that the pins 26or other gouging members can gouge out particles of desired size of theplastic composition from the sheet 29 as it is carried in adherentrelation o-n the surface of the roll 22. The roll 23 revolves on itsaxle 30 in a direction opposite to that of roll 22 as shown by thearrows in Fig..3 so that the gouging members move in the same directionas the travel of the sheet 29 on the r'oll 22. The scratcher roll isseparately driven by a variable speed motor (not shown) so as tomaintain a surface speed differential between the roll 23 and thecoacting sheeter roll 22 which can be varied at will. The scratcher rollis maintained at a-hgher peripheral speed than. that of the roll 22 andthe speed differential between these rolls preferably is at least about25 or more to 1 so as to facilitate clean separation of the particlesgouged from the sheet by the gouging members. Most of the sheet 29 isconverted to the particles or granules by the action of the gougingmembers and any plastic material remaining adherent to the roll 22 willreturn to the nip between the rolls 21 and 22. In this manner the hotplastic composition can be successfully converted into discreteparticles or granules under the controlled conditions hereinabovedescribed. Since the composition is mixed and formed into a sheet whichis carried on the roll 22 while maintaining the temperature controlsaforesaid it is apparent that the particles or granules as initiallyproduced are within the aforesaid temperature range, and preferably at atemperature which is not substantially below the mixing temperature.

The size of the granules produced by the scratcher roll depends largelyon the thickness of the sheet produced between the rolls 21 and 22, thespeed at which the scratcher roll is operated, the relative surfacespeeds of the scratcher roll and the coacting sheeter roll and the depthor penetration of the pins 26 or other gouging members into the body ofthe sheet 29. The pins 26 or other gouging members preferably are notpointed but are slightly tapered toward a flat outer tip. Moreover, theyare preferably positioned so as not to extend diametrically outwardlybut at an angle approximately 25 to the diameter of the roll 23 anddownwardly on the upwardly moving side of this roll. The clearancebetween the tips of the pins 26 and the metal surface of the roll 22preferably is not less than about .012. inch, and is less than about .25inch Further features of this invention are concerned with the formationof the heat pilasticized particles or granules in relation to subsequentcalendering and to the relative conditions under which these operationsare carried out. While the heat plasticized granules are preferablyproduced as above described and improved products are obtained when thisis the case, the further features and advantages of this inventionhereinafter described may also be realized if the heat plasticizedparticles or granules are produced in some other way.

In the manufacture of a plain or solid color sheet the particles orgranules immediately on their production are collected, after falling indiscrete condition through the atmosphere in the enclosure 24, on andadjacent the end of theV heated conveyer 31, and they are continuouslymoved out of the enclosure 24 at a controlled rate by the conveyor 31 tothe upper rolls 32 and 33 of a four roll calender. The provision ofmeans for supplying the particles or granules at a controlledrrate is animportant factor in obtaining desirable and uniform products. It will benoted that the rolls 32 are on about the `same level and rotate towardeach other at their upper surfaces so as to receive the granules 41(Fig.` l), the space above and betweenthemrserving asia hopper furtheparticles dischargedifromthe conveyer 31-as the particles are formedinto acontinuous Ysheet between the rolls 32y andi.4

The entire length of the conveyer 3l is preferably heated to maintain'the particles at a temperature which is approximately the same as thatof the particles as initially formed. Thus if the .particles areinitially formed at a temperature of about` 325 to 350 F. the particlesare maintained on the conveyer at a temperature within this range. Theconveyer may be heated electrically or by circulating hot gases throughthe ducts 32 and through a heat insulated enclosure 35. In Fig. 2 theadvancing portion 36 and the return portion 37 of the conveyer 31 areshown supported on rollers 38 movable on upper and lower tracks 39 and4t) respectively.

In the case of the formation of a sheet of plain or solid color thestock temperature of the particles or granules during calenderingbetween the rolls 32 and 33 may be substantially the saine as the stocktemperature during the mixing and particle formation steps and thetemperature of the rolls 32 and 33 may be controlled so as to maintainsuch stocktemperatures. As aforesaid, the stock temperatures may bewithin the aforesaid range of 300 to 375 F. and, more particularly, ifthe plastic composition is mixed at a temperature of about 325 to 350 F.

the stock temperature during calender-ing can be mainf tained withinthis temperature range, It is usually preferable to maintain thetemperature of the roll 33 at a slightly higher temperature than theroll 32 and the ternperature of the rolls may be maintained atapproximately stock temperatures or somewhat below when a sheet of plainor solid color is being produced.

By the foregoing steps a method of producing a sheet of solid or plaincolor is afforded which has several decided advantages. The steps of hotmixing, forming the mixed composition into a sheet, converting the sheetto heat plasticized particles and the formation of the heat plasticizedparticles into a second continuous sheet on a calender to which theparticles are fed, serves excellently for providing a sheet which is ofuniform consistency throughout due to the improved commingling of thecomposition ingredients which result from the initial sheet formationand the conversion of the sheet initially produced to particles whichare indiscriminately commingled and then reworked in being formed intothe second sheet. Moreover, the composition material as thus supplied tothe calender can be maintained under conditions of extremely uniformtemperature throughout so that more uniform calendering is afforded.Likewise the supply of the composition to the calender in the form ofheat plasticized granules more readily aids in the release of entrappedair, and extraction of foreign metallic particles from the plasticparticles, as by use of magnetic separators, is readily made possiblethereby preventing damage to the calender rolls. The operation is alsoone wherein continuous operation is made possible in a continuous mannerdue to the fact that the plastic mass as initially produced in a hotplastic and workable condition can be converted into particles withoutloss of heat whereby the particles as produced in the hot plasticcondition may beimmediately calendered.

The operations hereinabove described may be most advantageously employedin the production of a sheet of variegated color. In such case thegranules which are formed into a sheet between the rolls 32 and 33instead of all being the same color will be a predetermined mixture ofparticles or granules having different color. Thus heat plasticizedparticles having one color may be produced using the sheeter rolls 21and 22 and the scratcher roll 23 as hereinabove described and heatplasticized particles or granules of a different or contrasting colormay be introduced continuously and in controlled amount into theenclosure 24 from a hopper 42. The particles are introduced into theenclosure 24 from the hopper 42 so as to fall in discrete conditionthrough the air within the enclosure 24 and they become commingled withthe particles produced by the action of the scratcher roll 23 als thelatter particles likewise are falling through the air.

` 9 lt is thus seen that the heat plasticized particles of differentcolor are commingled while in essentially discrete condition in agaseous atmosphere so that when the particles are collected on and areconveyed away by the conveyer 31 the particles of diiferent color areuniformly distributed with each other as they are fed to the supply ofparticles 41 that is formed into a sheet by the rolls 32 and 33.

The particles in the hopper 42 are prepared in a manner similar to thatemployed in preparing the granules initially obtained in the enclosure24. Ordinarily they are of essentially the same composition as theparticles produced by the scratcher roll 23 except for difference incolor, although this is not essential provided the particles ofdifferent color are compatible or miscible with each other. Dependingupon the color combination desired in the iinal product, particles ofdesired color or colors are introduced into a hopper 43. The originalmaterials are mixed in a heated mixer, and the mix formed in the mixeris converted into the particles fed into the hopper 43 in a manneressentially similar to that hereinabove described. Thus, the mix isdeposited on the sheeter 44 which forms the mix into a sheet ashereinabove described in connection with the sheeter rolls '21 and 22;and a scratcher or gouging roll 45, which is similar in construction andoperation to the scratcher roll 23, converts the resulting sheet intoparticles or granules which are deposited in the hopper 43. Theconditions of temperature during the operations of mixing, sheeting andreduction to granular or particulate forrn are the same as thosehereinabove described in connection with mixer 20, the sheeter rolls 21and 22 and the scratcher roll 23.

The particles which are deposited in the hopper 43 are fed therefrominto a screw conveyer 46. The screw conveyer 46 deposits the particleson a heated conveyer 47 which is similar in construction and operationto the conveyer 31 and which is provided with an enclosure 48 havingducts 49 for heating gas, these parts being similar to the enclosure 35and the ducts 34 respectively associated with the conveyer 31. Theparticles are deposited by the conveyer 47 in the hopper 42 from whichthey are fed into the enclosure 24 to be mixed with the granulesprovided by the scratcher roll 23 in the manner above described. Theapparatus is continuously operative and provides granules at any rateneeded into the enclosure 24 to provide a desired proprtion of particleswhich are of a contrasting or different color as compared with theparticles produced by the scratcher roll 23. A supply of such particlesof contrasting color may be kept on hand or such particles may beprepared continuously and supplied at the required rate by adjusting thespeed of delivery of the screw conveyer 46. Preferably the conveyer 47operates at a fixed speed so that all the granules are heated for thesame length of time. By increasing or decreasing the amount of coloredparticles deposited by the conveyer 46 on the conveyer 47 the amount ofparticles of such color delivered to the main production line can bevaried as desired.

While the mixture of particles of different color as fed to the nipbetween the rolls 32 and 33 may be at a temperature within the rangehereinabove mentioned, it is preferable in the production of a sheet ofvariegated color that the granules as fed to the rolls 32 and 33 be at asomewhat lower temperature, namely, in the approximate range of 275 to325 F. It is desirable that the particles of different color all bepreheated to substantially the same temperature for being fed to thecalendar rolls 32 and 33.

-The temperature of the composition as it is calendered between therolls 32 and 33 may be in the range above indicated for the productionof 4a sheet of solid color. However, better color definition is affordedin the production Aof a sheet of variegated color when the compositionduring calendering is maintained at somewhat lower temperature, namely,in the approximate range of 250 F. to 325 F. Thus, the temperature ofthe composition is preferably from about 25 to about 75 below the mixingtemperature of the composition and the temperature of the composition asinitially converted into the form of particles or granules. Likewise forproviding improved color definition it is desirable that the temperatureof the calender rolls be maintained substantially below the temperatureof the composition as it is formed into a sheet from the particlessupplied to the calender rolls. For example, the calender roll 32 may bemaintained at a temperature in the approximate range to 190 F. while thecalender roll 33 may be maintained at a temperature in the approximaterange of 200 F. to 250 F. In such case the lower roll temperaturesmaintained will serve to cool the composition as it undergoescalendering so as to be substantially below the mixing temperature asabove mentioned. Preferably the roll 33 is operated at a peripheralspeed somewhat in excess of that of the roll 32, but this is notessential.

The calender rolls 32 and 33 of the four roll calender shown exercisetheprimary sheet forming and calendering functions. However the rolls 50and 51 of the calender may also be employed so that the calendersubjects the composition to three different calendering operations. Inany case the effect of the calendering is to produce a sheet ofvariegated color in the form of streaks having a jaspe appearance. Whenthe mixture of particles having different color is supplied to the rolls32 and 33 by the conveyer 31, the action of the rolls 32 and 33 is toform the particles into a continuous sheet having a jaspe appearancewherein the streaks are relatively short. By also passing the sheetbetween rolls 33 and 50 the sheet is further solidied and the streaksformed by the rolls 32 and 33 are further elongated. This action isaccomplished by a slight reduction in the thickness of the sheet and bymaintaining a small differential between the surface speeds of the rolls33 and 50. The sheet may be still further reduced in thickness by a passbetween` the rolls 50 and 51 which also have a surface speeddifferential thereby effecting further elongation of the streaks. Formost purposes passage of the mixture of variegated color imparted by theparticles solely between the rolls 32 and 33 produces a sheet ofdesirable color variegation in the form of jaspe streaks. In such caseby adjustment of the position of the rolls S0 and 51 the calenderingeffect of one or both of the rolls 50 and 51 may be omitted. In Fig. 1all four rolls of the calender are shown in operation. Alternatively itis possible to use the rolls 32 and 33 for calendering and the rolls 50and 51 as cooling rolls. The use of the rolls 50 and 51 as cooling rollsis particularly suitable in those cases when it is desired to produce afinished sheet having either a solid or plain color or havingvariegated` color of jaspe appearance.

The aforesaid temperatures and temperature differentials areillustrative of those appropriate in connection with a vinyl plasticcomposition of the typical formulation hereinabove described. Fordifferent compositions the temperature prevailing and maintained duringthe different steps may vary somewhat as compared with those hereinabovegiven depending primarily on such factors as the softening point of thevinyl resin used, the proportion and kind of filler, and the proportionand efficacy of the plasticizer, those combinations which acquiredesired consistency at a higher temperature being processed atcorrespondingly higher temperatures than those applicable in the case ofcompositions which acquire the same consistency at a somewhat lowertemperature. However, in such case the temperature dilferentials main-`tained would remain substantially as hereinabove stated.` While certaintemperature ranges have been indicated as occurring in the differentoperations andsteps in-L volved; the temperature that occurs in eachofthese operations` or steps is normally held as rigidly constantperatures are maintained uniform throughout the length of the roil sothat uniformity of the finished product will he maintained. Suchuniformity is readily accomplished in the practice of this invention aswell as exact duplication of results for different production runs. ltis important in this trade that a pattern of a given sample be capableof reproduction and substantial duplication, this being a matter thathas occasioned particular difiic'ulty in the past. However, the practiceof this invention affords a high degree of exibility in that by varyingthe conditions that are maintained, even relatively slightly, differentcolor, pattern, and other effects are obtainable. The principal factorsas regards pattern effects of variegated color are the temperatures andtemperature differentials maintained, the spacings between opposingcalender rolls, and the size of the bamk maintained at the nip betweenopposing calender rolls.

Products are obtainable at various stages inthe above process which areadapted to find many uses. The process yields pigmented plastic granulesor pellets of convenient sizes for handling in molding processes; andplain colored sheets and sheets of variegated color such as jaspe andmarbleized areiafforded in various thicknesses for various decorativepurposes.

The invention hereinabove set forth is embodied and utilized inparticular form and manner but may be variously embodied and utilizedwithin the scope of the claims hereinafter made.

I claim:

l. in a process of preparing a vinyl plastic product, the stepscomprising forming a heat plasticized vinyl plastic composition into asheet, making said sheet while at a temperature between about 300 F. toabout 375 F. firmly adherent to the surface of a heated rotating roll bysheeting said composition at the nip between said roll and an adjacentroll, and while said sheet is so adherent to the surface of said rolland is at said ternperature converting said sheet into heatedplasticized particles by gouging said particles therefrom by the actionof a multiplicity of gouging members which substantially penetrate saidsheet and are removed relative thereto while rotating about an-axisparallel to that of said roll at a peripheral speed at least twenty-tivetimes the peripheral speed of said composition on said adjacent rotatingroll and in the same direction as the composition on said adjacentrotating roll when said composition is in contact with said gougingmembers, any of said sheet not converted into said particles beingcarried on the surface of said roll back to said nip.

2. A method of making a vinyl plastic product which comprises mixingplasticizer, Vinyl resin and filler by mechanical mixing action whilesaid materials are heated to altemperature at which the mixed materialsare workable to effect substantially uniform commingling of saidmaterials by said mixing, and while the resulting mixture is maintainedat a temperature not substantially below the mixing temperatureperforming the further steps of forming the mixure into a continuoussheet, pressing said sheet to firmly adhere to and to be carried by thesurface of a rotating roll heated to maintain said sheet atsubstantially the mixing temperature, and while the sheet is so adheredto and carried by the surface of said rotating roll continuouslyconverting it into moldable heat plasticized particles by gouging saidparticles therefrom.

3. A method of making a vinyl plastic sheet which comprises the steps ofcontinuously forming into a sheet a vinyl plastic composition heated toa temperature at which it is of moldable and workable consistencywithinlthe range of about 300 F. to about 375 F., adhering the resultantheatedvsheet to the surface of a heatedrotating roll on .which it` iscontinuously carried throughV a substantialY distance, continuouslyconverting theheated. sheet while maintaining it within the saidtemperature range into moldable heat plasticized particlesrby gougingsaid particles therefrom while said sheet is adherently carried on thesurface of said heated rotating roll, collecting said moldable heatplasticized particles so-produced, and while maintaining their saidinoidable heat plasticized consistency continuously feeding them at asubstantially constant rate to calender rolls and forming them into acontinuous sheet by said calender rolls.

4. A method of producing a vinyl plastic sheet having a wear surface ofvariegated color which comprises mixing plasticizer, vinyl resin andfiller by mechanical mixing action while said materials are heated to atemperature at which the mixed materials are workable to effectsubstantially homogeneous commingling of said materials by said mixing,and while the resulting mixture is maintained at a temperature notsubstantially below the mixing temperature performing the further stepsof forming the mixture into a continuous sheet, pressing said sheet tofirmly adhere to and be carried by the surface of a rotating roll heatedto'maintain said sheet at substantially the mixing temperature, andwhile the sheet is so adhered to and carried by the surface of saidrotating roll conti'hously converting it into moldable heat plasticizedparticles by gouging said particles therefrom, commingling saidparticles while still retaining their heat with similar particles havinga dierent color to form a heated mixture of variegated color imparted bysaid particles and calendering the heated mixture while at a temperatureof about 25 F. to about 75 F. below said mixing temperature betweenrolls to form a calendered sheet of variegated color, the roll duringsaid calendering contacting the wear surface of the sheet beingmaintained at a higher temperature than the roll contacting the oppositeside of the sheet.

5. A method according to claim 4 wherein during said calendering thecalender roll surface in contact with the back surface of the resultingcalendered sheet is maintained at a temperature between about F. andabout F. and wherein the calender roll surface in contact with the wearsurface of said sheet is maintained at a substantially highertemperature within the range of about 200 F. to about 250 F.

6. A method of making moldable heat plasticized particles whichcomprises mixing pigment, plasticizer, vinyl resin and about 50 to about75 percent of filler while said materials are workable to effectsubstantially homogeneous commingling of said material by said mixingand while the resulting mixture is maintained at a temperature notsubstantially below the mixing temperature performing the further stepsof forming the mixture into a continuous sheet, pressing said sheet tofirmly adhere to and be carried by the surface of a rotating roll heatedto maintain said sheet at substantially the mixing temperature, andwhile the sheet is so adhered to and carried by the surface of saidrotating roll, continuously converting it into moldable heat plasticizedparticles by gouging said particles therefrom.

7. A method of making moldable heat plasticized particles whichcomprises mixing pigment, plasticizer, vinyl resin and about 50 to about75 percent of filler at a temperature between about 300 F. and about 375F. to effect substantially homogeneous commingling of said material bysaid mixing and while the resulting mixture is maintained at atemperature not substantially below the mixing temperature performingthe further steps of forming the mixture into a continuous sheet,pressing said sheet to firmly adhere to and be carried by the surface ofa rotating roll heated to maintain said sheet at substantially themixing temperature, and while the sheet is so adhered to and carried bythe surface of said rotating roll, continuously converting it intomoldable heat plasticized particles by gouging said particles therefrom.

8. A method of making moldable heat plasticized particles whichcomprises mixing pigment, plasticizer, filler and a polyvinyl chlorideresin while said materials are workable to effect substantiallyhomogeneous commingling of said material by said mixing and while theresulting mixture is maintained at a temperature not substantially belowthe mixing temperature performing the further steps of forming themixture into a continuous sheet, pressing said sheet to firmly adhere toand be carried by the surface of a rotating roll heated to maintain saidsheet at substantially the mixing temperature, and while the sheet is soadhered to and carried by the surface of said rotating roll,continuously converting it into moldable heat plasticized particles bygouging said particles therefrom.

9. A method of making moldable heat plasticized particles whichcomprises mixing pigment, plasticizer, filler and a polyvinyl chlorideresin at a temperature between about 300 F. and about 375 F. to effectsubstantially homogeneous commingling of said material by said mixingand while the resulting mixture is maintained at a temperature notsubstantially below the mixing temperature performing the further stepsof forming the mixture into a continuous sheet, pressing said sheet tofirmly adhere to and be carried by the surface of a rotating roll heatedto maintain said sheet at substantially the mixing temperature, andWhile the sheet is so adhered to and carried by the surface of saidrotating roll, continuously converting it into moldable heat plasticizedparticles by gouging said particles therefrom.

10. A method of making moldable heat plasticized particles whichcomprises mixing pigment, plasticizer, polyvinyl chloride resin andabout 50 to about 75 percent of filler at a temperature between about300 F. and about 375 F. to effect substantially homogeneous comminglingof said material by said mixing and while the resulting mixture ismaintained at a temperature not substantially below the mixingtemperature performing the further steps of forming the mixture into acontinuous sheet, pressing said sheet to rmly adhere to and be carriedby the surface of a rotating roll heated to maintain said sheet atsubstantially the mixing temperature, and while the sheet is so adheredto and carried by the surface of said rotating roll, continuouslyconverting it into moldable heat plasticized particles by gouging saidparticles therefrom.

11. The process of claim wherein the gouging is effected by the actionof a multiplicity of gouging members which substantially penetrate thesheet rrnly adhering on the rotating roll and are removed relativethereto While rotating about an axis parallel to that of the sheetcarrying roll at a peripheral speed at least twenty-live times theperipheral speed of the sheet on the adjacent rotating roll and in thesame direction as the sheet on said adjacent rotating roll when saidsheet is in contact with said gouging members.

12. A method according to claim 2 wherein said mixing temperature isbetween about 300 F. and 375 F., said continuous sheet is formed bypassing the composition between the nip formed by said rotating roll anda second roll and said gouging is effected by the action of amultiplicity of gouging members which substantially penetrate the sheetfirmly adhering on the rotating roll and are removed relative theretowhile rotating about an axis parallel to that of the sheet carrying rollat a peripheral speed at least twenty-live times the peripheral speed ofthe composition of the adjacent rotating sheet carrying roll and in thesame direction as the composition on said adjacent rotating roll whensaid composition is in contact with said gouging members, any of saidsheet not converted into said particles being carried on the surface ofsaid rotating roll back to said nip.

References Cited in the file of this patent UNITED STATES PATENTS Re.16,384 McCrohan July 13, 1926 Re. 21,390 Grote Mar. 12, 1940 653,312Pond July 10, 1900 690,238 Crean Dec. 31, 1901 1,763,314 McConougheyJune 10, 1930 1,939,045 Fredriksen Dec. 12, 1933 1,975,515 Mayer Oct. 2,1934 2,290,241 Kasen July 12, 1942 2,331,275 Perry Oct. 5, 19432,341,651 Raschig Feb. 15, 1944 2,451,597 Wheeler Oct. 19, 19482,512,523 Fisher et al. June 20, 1950 2,548,909 Ryden Apr. 17, 19512,551,005 Johnson May 1, 1951 2,608,717 Kay Sept. 2, 1952 2,624,514Wilhousky Jan. 6, 1953 2,625,712 Baby Jan. 20, 1953 2,689,981 McCarthySept. 28, 1954 2,740,991 Hess et al. Apr. 10, 1956

7. A METHOD OF MAKING MOLDABLE HEAT PLASTICIZED PARTICLES WHICHCOMPRISES MIXING PIGMENT, PLASTICIZER, VINYL RESIN AND ABOUT 50 TO ABOUT75 PERCENT OF FILLER AT A TEMPERATURE BETWEEN ABOUT 300* F. AND ABOUT375* F. TO EFFECT SUBSTANTIALLY HOMOGENOUS COMMINGLING OF SAID MATERIALBY SAID MIXING AND WHILE THE RESULTING MIXTURE IS MAINTAINED AT ATEMPERATURE NOT SUBSTANTIALLY BELOW THE MIXING TEMPERATURE PERFORMINGTHE FURTHER STEPS OF FORMING THE MIXTURE INTO A CONTINOUS SHEET,PRESSING SAID SHEET TO FIRMLY ADHERE TO AND BE CARRIED BY THE SURFACE OFA ROTATING ROLL HEATED TO MAINTAIN SAID SHEET AT SUBSTANTIALLY THEMIXING TEMPERATURE, AND WHILE THE SHEET IS SO ADHERE TO AND CARRIED BYTHE SURFACE OF SAID ROTATING ROLL, CONTINUOUSLY CONVERTING IT INTOMOLDABLE HEAT PLASTICIZED PARTICLES BY GOUGING SAID PARTICLES THEREFROM.